Reactions Induced inFe54with 21-63 MeVLi6Ions

Excitation functions have been measured for the production of ${\mathrm{Ni}}^{56}$, ${\mathrm{Ni}}^{57}$, ${\mathrm{Co}}^{55}$, ${\mathrm{Co}}^{56}$, ${\mathrm{Co}}^{57}$, ${\mathrm{Co}}^{58}$, ${\mathrm{Fe}}^{52}$, ${\mathrm{Fe}}^{55}$, and ${\mathrm{Mn}}^{54}$ from ${\mathrm{Fe}}^{54}$ bombarded with ${\mathrm{Li}}^6$ ions of 21-63-MeV kinetic energy. The targets were enriched to 95% ${\mathrm{Fe}}^{54}$. Excitation functions for the production of ${\mathrm{Ni}}^{57}$, ${\mathrm{Co}}^{55}$, ${\mathrm{Co}}^{56}$, ${\mathrm{Co}}^{57}$, ${\mathrm{Fe}}^{55}$, and ${\mathrm{Mn}}^{54}$ resulting from ${\mathrm{Li}}^6$ bombardment of ${\mathrm{Fe}}^{54}$ and deuteron bombardment of ${\mathrm{Ni}}^{58}$ are compared. Of these, excitation functions for the production of ${\mathrm{Ni}}^{57}$, ${\mathrm{Co}}^{57}$, and ${\mathrm{Mn}}^{54}$ are mutually consistent with decay of a ${\mathrm{Cu}}^{60}$ compound nucleus. Excitation functions for production of ${\mathrm{Co}}^{55}$ and ${\mathrm{Fe}}^{55}$ with the two projectiles appear to proceed by different mechanisms. The ${\mathrm{Co}}^{56}$ excitation functions in the two target-projectile systems are not directly comparable, since the probable reactions producing ${\mathrm{Co}}^{56}$ are ${\mathrm{Ni}}^{58}(d,\alpha ){\mathrm{Co}}^{56}$ and ${\mathrm{Fe}}^{54}({\mathrm{Li}}^6,2p2n){\mathrm{Co}}^{56}$. All excitation functions studied in the ${\mathrm{Fe}}^{54}$+${\mathrm{Li}}^6$ system show the competitive behavior of compound-nucleus reactions with the exception of the high-energy tail of the ${\mathrm{Co}}^{58}$ excitation function (apparently due to 5% ${\mathrm{Fe}}^{56}$ impurity in the targets) and the low-energy portions of the ${\mathrm{Co}}^{55}$ and ${\mathrm{Fe}}^{55}$ excitation functions. The very low yields observed for the production of ${\mathrm{Ni}}^{56}$ and ${\mathrm{Ni}}^{57}$ are attributed to the effect of the 28-nucleon shells on nuclear level densities. The sum of measured cross sections from ${\mathrm{Fe}}^{54}$+${\mathrm{Li}}^6$ reactions is compared with calculated optical-model nonelastic cross sections.